Extreme pressure lubricants



Nov. 8, 1949 Filed April 3, 1947 m/sen) amass-3&4

-TEM'PERATURE "F Patented Nov. 8, 1949 2,487,260 EXTREME PRESSURE LUBRICANTS Arnold J. Morway, Clark, N. 3., assignor to Standard Oil Development Company, a corporation of- Delaware Application April 3, 1947, Serial No. 7 39,172

4 Claims. 1

This inventon relates to extreme pressure lubricants, and in particular to extreme pressure lubricants such as greases containing carbon black as a grease-structure-imparting agent.

In the art of making lubricating greases, it is well known that the additon of certain oilsoluble compounds such as lead soaps and compounds comprising chlorine, sulfur, phosphorus and the like, improve the load-carrying capacity of the grease. Some of these compositions depend for their effect upon a strengthening of the lubricating film, whereas others depend upon a chemical reaction which takes place at elevated temperatures when metal parts come into contact as a result of lubricating film failure.

In a co-pending application, Serial No. 570,783, filed by the present applicant and John C. Zimmer jointly, dated December 30, 1944 (now abandoned), there is disclosed a grease composition comprising a mineral lubricating oil compounded with from 5% to 20% of a so-called structural carbon black, particularly an acetylene black, which gives to the oil a structural relationship characteristic of greases, as distinguished from a mere thickening which is characteristic of certa n loaded oils such as oils containing graphite and the like.

Asmore fully discussed in said co-pending application, certain acetylene blacks, have been found suitable for impartng the grease-like structure to the lubricarbon blacks, especially of the type mentioned above appear to form a collodal or a grease structure, apparently are related in some manner not clearly understood, to

' the particle size of the carbon with its related surface area and oil absorption characteristics.

. Acetylene blacks which have been found most suitable may, for example, have a pH rating of 7 about 7, and may be of such average particle size structure forming materials, are commonly of a cant, and have been termed structure blacks.

These carbon blacks are characterized by an apparent retculate structure, as observed under the high-power electron microscope. They are adapted to form colloidal gels in a variety of organic liquids. Such liquids may include those liquid petroleum distil'lates above the naphtha range. to which the structural carbon blacks impart a thickening effect quite similar to that of the grease-forming soaps, when the latter are compounded with mineral lubricating oils. The acetylene black and certain others, for example, those produced in the electric arc treatment of petroleum fractions, have this structural or oil absorbing property.

The structural characteristics whereby blacks lower pH value. With smaller particle size, the blacks become increasingly difllcult to disperse in oil and hence less practical to use. They are of more intense black color, and goodfor printing inks, paints, etc, but objectionable as grease ingredients'because of these properties.

In the co-pending application mentioned above, the structural carbon was employed primarily for the setting up of a grease structure with a mineral oil, other extreme pressure chemical agents being added to impart the extreme pressure characteristics to the lubricant. It has now been found that the effectiveness of certain commonly used extreme pressure ingredients may be increased by a choice of sutable nonstructural carbon blacks, i. e., those having less oil absorption capacity such as certain high modulus furnace blacks, e. g., one known commercially as Statex 93, in add'tion to the structural blacks mentioned above, and to accomplish this is anobject of my invention.

When materials such as sulfurized, chlorinated or phosphorized additives are incorporated in lubricants contaning structure blacks, it appears that such additives are at least partly absorbed by the blacks. As a result, they do not impart their full load-carrying properties to the greases. In addition, particularly in the lubrication of anti-friction roller bearings, it is not desirable. to incorporate highly chemically reactive extreme pressure additives, because these may cause corrosion at high temperatures, or may hydrolize under wet conditions to give corrosive products.

Notwithstanding the objection to the use of 3 chemically reactive extreme pressure additives in roller bearing lubricants, it is commonly required by bearing manufacturers that greases for anti-friction bearings have a fairly high extreme size of the structure black. Thus, a satisfactory black for the above purpose may be a high modulus furnace carbon black (HMF) su-h as a black sold by the Columbian Carbon Company as pr sur l adar i apa i y. F r xamp 5 "Statex 93." This black has a pH value of about the Timken Roller ar Compa y commonly and a surface area of about 4 to 6 acres per requires that greases designed for use with its pound. The average particle size appears to be bearin s hav a 3 p n satisfactory l which of the order of 50 to so millimlcrons in diameter, corre p n s to 20.000 p un p r square inch the particles tending to the spherical or particuload-carrying capacity. as measured by the 10 late form rather than the branched chain or ken extreme Pressure testing macmnereticulate form characteristic of acetylene black. While greases 0f the type described in appu' These blacks are relatively easily dispersed in cation Serial No. 570,783, mentioned hereinabove, mineral Du Smce with the larger particle stze. embodying merely structure blacks and extreme the black does not tend to agglomerate as readily Pressure additives, have mild extreme Pressure as the smaller particle size blacks. The smaller properties, they cannot pass the requirem particle size blacks are more acidic and one disjust mentioned. Hence a further object of the tinguishing characteristic of the non-structural present invention is to improve the load-bearing black' mentioned above is its high pH value, as characteristics of structure black greases without compared with the ordinary channel blacks the increasing their C'JHOSWitY' acetylene blacks being intermediate in this re- I have found that when a small amount of the spect Carbon blacks of high pH are desirable Structure black, Whether acetylene black to the extent that they contribute to oxidation analogous black as used in the greases disclosed stability of the gnaw in the Mesald appummnis The following table indicates the load-carryplaced with a non-structural carbon black, prefing properties of various carbon black greases erably of fairly large particle size, such as the tested accord: to th re t 1 ti Th high modulus furnace black referred to above, g e p F men e the I-Oadmearmg capacity of the grease is mate blacks such as those called Monarch 80 were flany improvei Thus when greases are ordinary channel blacks, and the lubricating oils pared as described in the aforesaid co-pending employed were refined mineral oils of 70 application, and are further compounded with viscosity at 210 F. It should be noted that grease so-called mild or non-corrosive extreme pressure containing only the channel blacks acetylene additives which are well known in the art, such blacks on the n n 1 n in nly the greases are found capable of carrying only a less oil absorptive black such as the high modulus 24 pound satisfactory load, when tested on the 35 furnace black "Statex 93, on the other hand, Timken machine. When a small amount of the were relatively unsatisfactory in certain respects, structure black is replaced with less oil-absorptive whereas a grease combining the two types of black, the load-bearing capacity using the same blacks passed the 33 pound test and even the 43 extreme pressure additive, increases to 33 pounds pound test without any difllculty.

TABLE I Load-carrying properties of carbon black creases Load-C Capacity as Measured by the Tim en Extreme Pressure Testing Grease Composition Macmne 8# 1o: 24: sai or 18.07 Ink black ("Monarch 80"), 81.0% Refined mineral oil, S at 210 F., 1.0% pass.-. iai1.

Pofyisobutylene solution. 18.07 Ink black (Monarch 80"), 20.0% Pb oleote conc. (60-50 min. oil. cone.) 1.0% pass.-. pass... iail.

Polyisobutylene solution, 10.0% Suliurized fatty oil (8.5% 8.), 51.0% Refined min. oil. 20.0% High modulus furnace black (Stotox 93), 1.0% Polyisobutylene solution, 79.0% pass..- mum.

Refined min. oil. (Does not make a good grease. 20.0% Acetylene black, 1.0% Polyisobutylene solution, 79.0% Refined min, 0 do do 12.0% Acetylene black, 1.0% Polyisobutylene solution, 20.0% Pb oleate cone, in min, fail--- oil, 20.0% P483, 65.0% Refined mm. oil. Acetylene black, 1.0% Poiyisobutylenc solution, 20.0% Pb oleate cone. in min. .do ...do..

o 5.0% nrd oll suliurized 20%, 62.0% Refined min. oil. 12.0% Acetylene black, 1.0% Polyisobutylene solution, 20.0% Pb oleate cone, in min, do .do

oil, 7.5% S1011 treated lard oil (cutting oil base), 59.5% Refined min. oil. 12.0% Acetylene black, 1.0% Polyisobutylene solution 20.0% Pb oleate cone. in min. do- .do..

oil 7.5% Sulfurized i'attfipil, 8.5% 8., 59.5% Refine min. oil. 10% Acet lene black, 6% l h modulus furnace black (Statex so), 20 Lead oleato do pass. pass.

conc. min. oil, 1% Poly sobutylene solution, 7.5% Suliurlzed fatty oil, 8.5% 8., 55.5% Refined min. oil.

1 1'7 polyisobutylene solution is 1'7 by Weight of a mineral oil solution containin 6 b Wei ht of isobut lone polymer of 50,000 to 100,060 molecular weight. Actual polyisobutylcne content is .06%. g y g y and even up to 43 pounds or more satisfactory Timken load, thus rendering such greases suitable for the lubrication of Timken roller bearings without adding more potent but objectionably corrosive types of extreme pressure agents.

The less oil-absorptive black which is preferably employed is not greatly different in particle size from acetylene black, although the average ultimate particle size may be somewhat larger. It

The mineral 0115 mentioned above were all of 70 SSU viscosity at 210 F. The polyisobutylene compound was added to increase the tackiness of the grease.

Inasmuch as greases of the foregoing character may be used under conditions where considerable heat develops, and also where water may gain access or where water may be released as a result of chemical reaction of special additives, tests were should not be more than about twice the particle 15 also made as to the effects of heat and water on aeemoo TABLE 11 type, such as the high modulus furnace carbon black of the State: 93" type.

Lubricant Conditions oi anti-friction bearing cup after contact with the wet rease for 24 hours at 340-345" F.

6.0% High modulus furnace black (State): 03), 10.07 Acetylene black 1.0%

20.0% Pb oleate cone. in min. oil, 63.0% Refine coastal oil-70 contact with greme. Same grease base contalninc 2.0% chlorinated wax (40% chlorine -typical commercial extreme pressure additive for greases) in place of suliuriaed fatty oil, 335% water in contact with grease.

Polyisobutylene solution, SUM 210 F., 334% water in Unchanged, Like Original.

Darkened and corroded.

An example of a suitable composition for a mild E. P. 'base oil suitable for use in greases of the foregoing character has The sperm oil was heated to 380 F. and the sulfur added. The temperature was maintained at 380-385 F. for 90 minutes, and the mineral oil added at the end of that period. The temperabeen found to be as 'ture was then reduced to 200 F. as rapidly as pos- I sible to eliminate further sulfuriaation.

Sulfur analysis per cent=8.5.

A carbon black grease may be prepared according to the following formula:

. Per cent High modulus furnace black (Statex 93) 6.0 Acetylene black 10.0 Polyisobutylene solution 1.0 Lead oleate 10.0 Sulfurized fatty oil 10.0 Mineral oil 70 SSU at 210 F 63.0

ature may be raised, but since little or no thinning out of the grease occurs with a rise in tem- Tests show that the carbon black greases of my invention are much more consistent in viscosity and structure over a wide temperature range, than is the case with certain standard recognized high temperature greases. The attached drawing shows the temperature-pressure characteristics of a grease containing the mixture of particulate and reticulate blacks as compared with a typical'soap thickened grease currently sold on the market for lubrication at elevated temperature.

' While I have indicated that various percentages of various types of carbon blacks may be used in greases, it will be understood that the proportions may vary according to the load-carrying characteristics desired, consistency, viscosity of the lubricant, E. P. additives used, and other variables. Thus, the percentage of particulate carbon black, 1. e., the black of relatively lower grease-structure properties, may vary from a very small fraction to as much as or more than the amount of acetylene or other highly absorptive black used. The. latter black may vary from 3 to 20% by weight of the entire grease. and the perature, no particular advantage is gained.

Paddle speeds should not be too fast at first or the black which is very light and fluffy may be blown out of the kettle. When the black and oil starts to ball up, more oil is added, working out to a smooth grease. When all the oil is in and the resultant grease smooth, the lead oleate is heated to approximately 200 F. to facilitate handling and then is charged and worked into the mass. Some softening usually occurs when the lead oleate is added. If facilities for heating the lead oleate are not available, the temperature of the grease in the kettle may be raised to 200 F. and the lead oleate concentrate then added. The sulfurized fatty oil is then added and thoroughly incorporated into the grease. The polyisobutylone is added last. The product having a worked penetration of 340/360 ram/10 is then filtered through equipment similar to that used on calcium greases and packaged.

Greases of this type, having a heavier consistency than that described above, may be prepared by increasing the carbon black. I have noted that greases containing 20% or more of carbon black set back to re'atively hard products, which readily break down on very slight working to their original consistency.

As indicated above, it is preferred that the carbon black he divided between a reticulate or chain-like structure black and a particulate to A of the carbon black will be of the latter less absorptive black may vary from 0.5 to 10% ormore. Various additives, such as antioxidants, corrosion inhibitors and the like, may be incorporated, as will 'be understood by those skilled in the art. The total carbon black content will ordinarily run between 5 and 25% by weight, based on the total composition.

As indicated above, the oil soluble polymer such as a polyisobutylene, used to impart adhesive properties, is preferably added as a concentrated all solution. A desirable additive is a 6% solution in mineral oil, from 0.1 to 3% of such solution be ing added, based on the total grease composition. The actual polymer content of the finished grease is therefore from 0.006 to 0.18%, a content of about 0.05% to 0.10% being preferred.

I claim:

1. A composition consisting essentially of 2. A composition substantially as given in claim 1 where the non-corrosive extreme pressure agent is sulfurized sperm oil.

3. An antifriction-bearing lubricant consisting essentially of a major proportion of lubricating oil, 5 to 25% carbon black including both a major proportion of acetylene and a minor proportion of high modulus carbon blacks, 2 to 15% lead oleate, 2 to 15% sulfurized fatty oil, and 0.05 to 0.10%,of an oil soluble polymer capable of imparting adhesive properties to said composition,

7 said composition being non corrosive to said b arlnfls.

4. An extreme pressure lubricant comprising at least 60% mineral lubricating oil, 5 to 25% carbon black containing 8 to 20 parts of acetylene 5 black and 0.5 to 10 parts of high modulus black. the acetylene black being always present in larger amount than said high modulus black and a metalsoap, a tackiness agent, and a non-corro sive extreme pressure agent.

ARNOLD J. MORWAY.

REFERENCES CITED The following references are of record in the file of this patent:

OTHER REFERENCES Rubber Age, August l944,'artic1e by Sweitzer o and Goodrich entitled The Carbon Spectrum for the Rubber Compounds," page 470.

Can. Chem. & Process Ind., March 1944, article by Wiegand entitled Recent Developments in Colloidal Carbon," page 160. 

